For example, server computers are located in the room of the data center. For example, a blower fan unit is mounted on the top panel of the rack that accommodates the server computers. Air current generated by the blower fan unit stirs the air in the room. As a result, warm air with heat given off from the server computers mixes with relatively cold air surrounding the server computers. Thus, excessive temperature rise in the room of the data center is prevented.
The blower fan unit includes a centrifugal fan that rotates around a rotation center axis. The outlet is formed in a centrifugal direction from the rotation center axis in the housing that accommodates the centrifugal fan. The air current generated on the basis of driving the centrifugal fan is exhausted through the outlet. As a result, the housing rotates around the rotation center axis. The air current flows in a 360-degree circle around the rotating center axis. In the blower fan unit, the air current is only generated along an orthogonal virtual plane to the rotation center axis.
Japanese Laid-open Patent Publication No. 2007-278182, Japanese Laid-open Patent Publication No. 2002-364597, Japanese Laid-open Patent Publication No. 2008-520104, Japanese Laid-open Patent Publication No. 2004-55656 and Japanese Laid-open Patent Publication No. 2004-44938 are examples of related art.